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1772-6.8.3, 19 - special programming techniques, 19ć1, Special programming techniques – Rockwell Automation 1772-LP3 PLC - 2/30 Programmable Controller Programming and Operations Manual User Manual

Page 306

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Chapter

19

19Ć1

Special Programming Techniques

There are several programming techniques that offer versatile control of
the process of machine operation. They include:

One-Shot

The one-shot programming technique uses a scan counter to set a bit on for
one scan only. There are two types of one-shots that can be programmed.

Leading

Edge

Trailing

Edge

A leading edge one-shot is used to set a bit on for one scan when the input
condition has made a false-true transition. The transition represents the
leading edge of the input pulse. The programming for a leading edge
one-shot is shown in Figure 19.1.

Figure 19.1

Leading Edge OneĆShot

Input Pulse: Bit 112/04

OneĆshot Bit: Bit 203/00

|ą|

04

112

|ą|

00

Application Program...

203

( SCT )

203

PR 002

AC 000

ON

OFF

ON

OFF

One Scan

Leading Edge

19.0
General

19.1
One Shot

19.1.1
Leading Edge OneĆShot